#!/bin/sh
# Scriptname: do_increment
increment ()  {
	sum=`expr $1 + 1`
	return $sum	  # Return the value of sum to the script.
} 
echo  -n "The sum is "
increment 5    # Call function increment; pass 5 as a
               # parameter. 5 becomes $1 for the increment 
               # function.
echo $?        # The return value is stored in $?
echo  $sum     # The variable "sum" is known to the function, 
               # and is also known to the main script.
               